The present invention relates to a structural element of closed-cell polyurethane rigid foam having good thermal insulation and improved sound absorption characteristics.
Polymer foam panels, in particular, polyurethane rigid foams, are used in a variety of applications for building insulation. In the roof insulation sector, panels between 40 mm and 180 mm thick are used, for example, as mountable insulation materials. The main object of these panels is to ensure thermal insulation. For this purpose, the materials used generally have a thermal conductivity in the range from 20 to 35 mW/mK. If flexible outer layers are used, this thermal conductivity value can be improved still further. In addition, a compression strength of at least 0.10 N/mm2 must be provided because the load-bearing capacity for roofing materials must be ensured when laying these panels. Panel materials that in addition to thermal insulation also ensure sound insulation against external noise and that also prevent sound conduction between rooms, in particular in a frequency range from 1000 Hz to 5000 Hz, would be advantageous.
Surface-compacted, perforated polyurethane foam molded parts used for insulating apparatus housings are described in DE-A 199 62 865. Sound absorption is achieved by virtue of the fact that the skin-covered foams are pierced in the vicinity of the surface and the soundwaves can thus penetrate the foam. A disadvantage, however, is that the foams described therein have neither sufficient compression strengths nor thermal insulating properties.